Heating element and manufacturing method thereof

ABSTRACT

Provided are a heating element, which includes: a transparent substance; a conductive heating line that is provided on at least one side of the transparent substance; bus bars that is electrically connected to the conductive heating line; and a power portion that is connected to the bus bars, wherein 30% or more of the entire area of the transparent substance has a conductive heating line pattern in which, when the straight line that intersects the conductive heating line is drawn, a ratio (distance distribution ratio) of standard deviation in respects to an average value of distances between adjacent intersection points of the straight line and the conductive heating line is 2% or more, and a method for manufacturing the same.

TECHNICAL FIELD

The present invention relates to a heating element and a method formanufacturing the same. More particularly, the present invention relatesto a heating element that includes a pattern that is not well visible,has excellent heating performance at a low voltage, and is capable ofminimizing diffraction and interference of light, and a method formanufacturing the same.

BACKGROUND ART

In winter or rainy day, frost is formed on a glass surface of a vehiclebecause of a difference between temperatures of the outside and insideof the vehicle. In addition, in the case of an indoor ski resort, afreezing phenomenon occurs because of a difference between temperaturesof the inside where there is a slope and the outside of the slope. Inorder to solve this, a heating glass has been developed. The heatingglass uses a concept where after a hot line sheet is attached to theglass surface or a hot line is directly formed on the glass surface, acurrent is applied to both terminals of the hot line to generate heatfrom the hot line, thereby increasing the temperature of the glasssurface. It is important that the heating glass for vehicle orconstruction has low resistance in order to smoothly generate heat, butit should not be offensive to human eye. Accordingly, methods formanufacturing a known transparent heating glass by forming a heatinglayer through a sputtering process using a transparent conductivematerial such as ITO (Indium Tin Oxide) or Ag thin film and connectingan electrode to a front end thereof have been proposed. However, theheating glass according to the above method has a problem in that it isdifficult to drive it at a low voltage of 40 V or less because of highsurface resistance.

DISCLOSURE Technical Problem

In order to solve the above problems, the present invention has beenmade in an effort to provide a heating element that is not well visible,can minimize side effects by diffraction and interference of singlelight source after sunset and has excellent heating performance at a lowvoltage, and a method for manufacturing the same.

Technical Solution

In order to accomplish the above object, an exemplary embodiment of thepresent invention provides a heating element comprising a transparentsubstance; a conductive heating line that is provided on at least oneside of transparent substance; bus bars that is electrically connectedto the conductive heating line; and a power portion that is connected tothe bus bars, wherein 30% or more of the entire area of the transparentsubstance has

a conductive heating line pattern in which, when a straight line thatintersects the conductive heating line is drawn, a ratio (distancedistribution ratio) of standard deviation in respects to an averagevalue of distances between adjacent intersection points of the straightline and the conductive heating line is 2% or more. The straight linethat intersects the conductive heating line means a line where thedistance deviation of the most closely adjacent intersection points ofthe pattern that is generated by the line is small. In addition, it maybe a line that vertically extends in respects to the tangent line of anyone point.

Another exemplary embodiment of the present invention provides a heatingelement, which includes: a transparent substance; a conductive heatingline that is provided on at least one side of the transparent substance;bus bars that is electrically connected to the conductive heating line;and a power portion that is connected to the bus bars, wherein thestandard deviation value of the intensity light for each 5° in acircumferential direction of the light source which is measured when thelight emitted from the light source that is disposed at the distance of7 m from the heating element passes through the heating element is 15 orless.

Still another exemplary embodiment of the present invention provides amethod for manufacturing a heating element, which includes: forming aconductive heating line on a transparent substance; forming bus barsthat is electrically connected to the conductive heating line; andforming a power portion that is connected to the bus bars, wherein, on30% or more of the entire area of the transparent substance, the heatingelement is formed in a pattern in which, when a straight line thatintersects the conductive heating line is drawn, a ratio (distancedistribution ratio) of standard deviation in respects to an averagevalue of distances between adjacent intersection points of the straightline and the conductive heating line is 2% or more. The conductiveheating line may be formed by using a printing method, aphotolithography method, a photography method, a method using a mask, asputtering method, or an inkjet method.

Advantageous Effects

According to the exemplary embodiments of the present invention, theheating element can minimize side effects by diffraction andinterference of single light source after sunset, has excellent heatingperformance at a low voltage and is not well visible. In addition, sincethe heating element according to an exemplary embodiment of the presentinvention can be formed by using various methods such as using aprinting method, a photolithography method, a photography method, amethod using a mask, a sputtering method, or an inkjet method after adesired pattern is previously set, the process is easily performed andthe cost is low.

DESCRIPTION OF DRAWINGS

FIG. 1 and FIG. 2 illustrate a state in which a predetermined straightline is drawn on a heating line pattern of a heating element accordingto an exemplary embodiment of the present invention.

FIG. 3 is a view that illustrates an offset printing process.

FIG. 4 illustrates forming the pattern by using the Voronoi diagramaccording to an exemplary embodiment of the present invention.

FIG. 5 illustrates the pattern of the conductive heating line of theheating element according to an exemplary embodiment of the presentinvention.

FIG. 6 and FIG. 7 illustrate the conductive heating line pattern of theheating element according to the related art.

FIG. 8 illustrates an equipment configuration for measuring theintensity of light that passes through the heating element according toan exemplary embodiment of the present invention.

FIG. 9 illustrates the measurement results of scattering properties ofthe heating bodies that are manufactured in Example 1 and ComparativeExample 1.

BEST MODE

Hereinafter, the present invention will be described in detail.

A heating element according to an exemplary embodiment of the presentinvention includes a transparent substance; a conductive heating linethat is provided on at least one side of the transparent substance; busbars that is electrically connected to the conductive heating line; anda power portion that is connected to the bus bars, wherein 30% or moreof the entire area of the transparent substance has a conductive heatingline pattern in which, when a straight line that intersects theconductive heating line is drawn, a ratio (distance distribution ratio)of standard deviation in respects to an average value of distancesbetween adjacent intersection points of the straight line and theconductive heating line is 2% or more.

As shown in the related art, in the case of when the transparent frontside heating layer is formed, there is a problem in that resistance isvery high. In addition, in the case when the heating line is formed in aregular pattern having one or more shapes such as a grid manner orlinear manner, diffraction and interference patterns of light may begenerated by a difference between refractive indexes of the heating lineand transparent substance. The patterns maximize the effect by the lightsource that is present after sunset such as headlight of the vehicle orstreetlamp. Therefore, in the case of when the heating element that hasthe heating line is applied to the front window of the vehicle, thediffraction and interference patterns of light as described above maymake safety and the degree of fatigue of the driver serious.

In the present invention, as described above, it is possible to preventside effects by the interference of the light source that can bedetected by the naked eye in a dark area because 30% or more, preferably70%, and more preferably 90% or more of the entire area of thetransparent substance has the pattern where, when the straight line thatintersects the conductive heating line is drawn, the ratio (distancedistribution ratio)of the standard deviation in respects to the averagevalue of distances of the adjacent intersection points of the straightline and the conductive heating line is 2% or more.

In the present invention, it is preferable that the straight line thatintersects the conductive heating line is a line in which the standarddeviation of the distances between adjacent intersection points of thestraight line that intersects the conductive heating line and theconductive heating line is the smallest value. In addition, it ispreferable that the straight line that intersects the conductive heatingline is a straight line that vertically extends in respects to thetangent line of any one point of the conductive heating lines.

In the heating element according to an exemplary embodiment of thepresent invention, it is preferable that the straight line thatintersects the conductive heating line has 80 or more intersectionpoints with the conductive heating line.

The ratio (distance distribution ratio) of standard deviation inrespects to an average value of distances between adjacent intersectionpoints of the straight line that intersects the conductive heating lineand the conductive heating line is preferably 2% or more, morepreferably 10% or more, and even more preferably 20% or more.

It is preferable that the pattern in which the ratio (distancedistribution ratio) standard deviation in respects to an average valueof distances between adjacent intersection points of the straight linethat intersects the conductive heating line and the conductive heatingline is preferably 2% or more is 30% or more in respects to the entirearea of the transparent substance. As described above, the other typeconductive heating line may be provided on a portion of the at least oneside of the surface of the transparent substance that is provided withthe heating line pattern.

In the present invention, as described above, by making the pattern ofthe heating line irregular, it is possible to provide the heatingelement that has the optical property where the standard deviation valueof the intensity of light for each 5° in a circumferential direction ofthe light source which is measured when the light that is emitted fromthe light source that is disposed at the distance of 7 m from theheating element passes through the heating element is 15 or less. Bythis physical property, it is possible to prevent side effects by theinterference of the light source that can be detected by the naked eyein a dark area.

Since there may be present a deviation according to the kind of lightsource, in the present invention, as the standard light source, anincandescent lamp of 100 W is used. The intensity of light is measuredthrough a digital camera. The photographing condition of the camera isset so that, for example, F (aperture value) is 3.5, a shutter speed is1/100, ISO is 400 and a black and white image is ensured. After theimage is obtained by using the camera as described above, the intensityof light may be rated through an image analysis.

In the present invention, when the intensity of light is measured, thelight source is disposed at the center of the black box that has thewidth of 30 cm, length of 15 cm, and the height of 30 cm, and theequipment where the circle that has the diameter of 12.7 mm is openedbefore the point of 7.5 cm from the center of the light source is used.The light source of the double phase measurement equipment deviceaccording to KS L 2007 standard is adopted. The digital image that isobtained by using the above condition is stored in 1600×1200 pixels, theintensity of light per each pixel is represented by the numerical valuein the range of 0 to 255, and the area in the light source area per eachpixel has the value in the range of 0.1 to 0.16

On the basis of the intensity of light per the pixel of the digitalimage, on the basis of the sum total of the left, right/upper and lowerintensities, the position of the central pixel of the light source isobtained. On the basis of the central pixel of the light source, theaverage value f the intensities of light for each 5° by dividing the sumtotal of intensities of light of the pixel that corresponds to the angleof 5° by the number of the pixel. In the pixel that is used I thecalculation, all pixels of 1200×1600 are not used, but when it isassumed that one pixel corresponds to the distance 1 by reducing thepixel as the coordinate value, only pixels that are present within thedistance of 500 or less from the central pixel of the light source areused. Since the average value is calculated as one value for each 5°, ifit is reduced into 360°, 72 values are obtained. Therefore, the standarddeviation that is calculated in the present invention is a value thatcorresponds to 72 standard deviations.

It is preferable that the measurement of the intensity of light isperformed in the dark room. FIG. 8 illustrates the configuration of theequipment.

In the present invention, when light that is emitted from the lightsource that is distant from the heating element by 7 m penetrates theheating element, the standard deviation value of the intensities oflight that is measured per each 5 in a circumferential direction oflight source is 15 or less, more preferably 13 or less, and morepreferably 10, and much more preferably 5 or less.

Meanwhile, in the case of when the patterns are completely irregular, inthe distribution of the line, there may be a difference between a looseportion and a dense portion thereof. The distribution of the line may bevisible by the eye even though the line width is very thin. In order tosolve this problem of sight recognition, in the present invention, whenthe heating line is formed, regularity and irregularity may beappropriately harmonized. For example, the basic unit is set so that theheating line is visible or local heating is not formed, and in the basicunit, the heating line may be formed in an irregular pattern. If theabove method is used, the visibility can be compensated by preventingthe localization of the distribution of lines on the one point.

As described above, for the uniform heating and visibility of theheating element, it is preferable that the opening ratio of the patternis constant in the unit area. It is preferable that the permeabilitydeviation of the heating element is 5% or less in respects to apredetermined circle that has the diameter of 20 cm. In this case, theheating element may prevent the local heating. In addition, in theheating element, it is preferable that after the heating, the standarddeviation of the surface temperature of the transparent substance iswithin 20%.

In the present invention, the heating line may be formed of the straightlines, or various modifications such as curved lines, wave lines, andzigzag lines may be feasible.

FIG. 1 and FIG. 2 illustrate a state in which a predetermined line isdrawn on a pattern of a conductive heating line according to anexemplary embodiment of the present invention. However, the scope of thepresent invention is not limited thereto. FIG. 1 illustrates an onedimension state in which the conductive heating lines do not cross eachother, and FIG. 2 illustrates a two dimension state in which theconductive heating lines cross each other and a closed figure is formedon some areas. An example of the other conductive heating line patternis illustrated in FIG. 5, but the scope of the present invention is notlimited thereto.

According to an exemplary embodiment of the present invention, theconductive heating line pattern may be a boundary shape of the figuresthat form a Voronoi diagram.

In the present invention, side effects by diffraction and interferenceof light can be minimized by forming the conductive heating line patternin a boundary form of figures that configure the Voronoi diagram. TheVoronoi diagram is a pattern that is formed by filling the closest areafrom the corresponding dot as compared to the distance of the dot fromthe other dots if Voronoi diagram generator dots are disposed in an areathat will be filled. For example, when large discount stores in thewhole country are represented by dots and consumers find the closestlarge discount store, the pattern that displays the commercial area ofeach discount store may be exemplified. That is, if the space is filledwith regular hexagon and each dot of the regular hexagon is set by theVoronoi generator, the conductive heating line pattern may be ahoneycomb structure. In the present invention, in the case of when theconductive heating line pattern is formed, there is an advantage in thatthe complex pattern form that can minimize the side effects by thediffraction and interference of light can be easily determined. FIG. 4illustrates the forming of the pattern using the Voronoi diagramgenerator.

In the present invention, the pattern that is obtained from thegenerator may be used by regularly or irregularly positioning theVoronoi diagram generator.

In the case of when the conductive heating line pattern is formed in aboundary form of the figures that form the Voronoi diagram, as describedabove, in order to solve the recognition problem, when the Voronoidiagram generator is generated, the regularity and irregularity may beappropriately harmonized. For example, after the area having apredetermined size is set as the basic unit in the area in which the patis provided, the dots are generated so that the distribution of dots inthe basic unit has the irregularity, thus manufacturing the Voronoipattern. If the above method is used, the visibility can be compensatedby preventing the localization of the distribution of lines on the onepoint.

As described above, in the case of when the opening ratio of the patternis made constant in the basic unit area for the uniform heating andvisibility of the heating element, it is possible to control the numberper unit area of the Voronoi diagram generator. In this case, when thenumber per unit area of the Voronoi diagram generator is uniformlycontrolled, the unit area is preferably 5 cm² or less and morepreferably 1 cm² or less. The number per unit area of the Voronoidiagram generator is preferably 25 to 2,500/cm² and more preferably 100to 2,000/cm².

Among the figures that form the pattern in the unit area, at least onehas preferably the different shape from the remaining figures.

In the present invention, in the case of when the heating line patternis formed on the transparent substance by using the following method,the line width and line height may be made uniform. According to anexemplary embodiment of the present invention, at least a portion of theconductive heating line pattern may be different from the remainingpattern. The desired heating line pattern may be obtained by thisconfiguration. For example, in the vehicle glass, in order to ensure theview field first in the area which corresponds to the front surface ofthe driver, the heating line patterns of the corresponding area and theremaining area may be different from each other. The line widths andline intervals of the printing pattern may be different from each otherso that at least a portion of the heating line pattern is different fromthe remaining printing pattern. Therefore, the heating may more rapidlyor efficiently occur at a desired place.

According to an exemplary embodiment of the present invention, theheating element may include an area in which the conductive heating lineis not formed. Transmission and reception that have a predeterminedfrequency can be performed by allowing at least a portion of the heatingelement not to form the conductive heating line, and informationtransmission and reception may be performed between the internal spaceand the external space. In this case, the area in which the conductiveheating line is not formed may have an area that varies according to thedesired frequency of the transmission and reception. For example, inorder to pass the electromagnetic wave of 1.6 GHz that is used in theGPS, the area that has the long side that is ½ (9.4 cm) or more of theabove wavelength is required. The area in which the conductive heatingline is not formed may have an area that can transmit and receive thedesired frequency, and its form is not particularly limited. Forexample, in the present invention, in order to pass the electromagneticwave, the area in which the conductive heating line is not formed maythe heating element that is provided with one or more semicircular areasthat have the diameter of 5 to 20 cm.

According to an exemplary embodiment of the present invention, theconductive heating line may be blackened. If the paste that includes themetal material is sintered at the high temperature, metal gloss isshown, such that the visibility may be lowered because of the reflectionof light. The problem may be prevented by blackening the conductiveheating line. In order to blacken the conductive heating line, theblackening material may be added to the paste for forming the heatingline or the blackening treatment may be performed after the paste isprinted and sintered, thereby blackening the conductive heating line.

As the blackening material that may be added to the paste, there aremetal oxide, carbon black, carbon nanotube, black pigment, colored glassfrit and the like. In this case, the composition of the paste mayinclude 50 to 90 wt % of the conductive heating line material, 1 to 20wt % of organic binder, 1 to 10 wt % of blackening material, 0.1 to 10wt % of glass frit, and 1 to 20 wt % of solvent.

When the blackening treatment is performed after the sintering, thecomposition of the paste may include 50 to 90 wt % of the conductiveheating line material, 1 to 20 wt % of organic binder, 0.1 to 10 wt % ofglass frit, and 1 to 20 wt % of solvent. The blackening treatment afterthe sintering includes dipping into the oxidized solution, for example,solution that includes the Fe or Cu ion, dipping into the solution thatincludes halogen ions such as a chlorine ion, dipping into hydrogenperoxide and nitric acids, and treatment using the halogen gas.

In order to maximize the minimization effect of side effects by thediffraction and interference of light, the conductive heating linepattern may be formed so that the area of the pattern that is formed ofthe figures having the asymmetric structure is larger than the entirepattern area by 10% or more. In addition, it may be formed so that thearea of the figures in which at least one of the lines that connect thecentral point of any one figure that forms the Voronoi diagram and thecentral point of the adjacent figure forming the boundary in conjunctionwith the figure is different from the remaining lines in views of lengthis larger than the entire conductive heating line pattern area by 10% ormore.

When the heating line pattern is manufactured, after the pattern isdesigned in a limited area, the method in which the limited area isrepeatedly connected is used to manufacture a large area pattern. Inorder to repeatedly connect the patterns, the repetitive patterns may beconnected to each other by fixing the positions of the dots of eachquadrilateral. In this case, the limited area has the area of preferably1 cm² or more and more preferably 10 cm² or more in order to minimizethe diffraction and interference by the repetition.

In the present invention, after the desired pattern form is determinedfirst, the precise conductive heating line pattern that has the thinline width may be formed on the transparent substance by using aprinting method, a photolithography method, a photography method, amethod using a mask, a sputtering method, or an inkjet method. When thepattern form is determined, the Voronoi diagram generator may be used,such that a complex pattern form may be easily determined. Here, theVoronoi diagram generator means the dots that are disposed so that theVoronoi diagram is formed as described above. However, the scope of thepresent invention is not limited thereto, and the other method may beused in addition to the method for using the Voronoi diagram when thedesired pattern form is determined.

The printing method may be performed by using a method in which thepaste that includes the conductive heating line material is transferredon the transparent substance in the desired pattern form and sintered.The transferring method is not particularly limited, but the abovepattern form is formed on the pattern transferring medium such as aintaglio or screen and the desired pattern may be transferred on thetransparent substance by using this. The method for forming the patternform on the pattern transferring medium may be performed by using themethod that is known in the art.

The printing method is not particularly limited, and a printing methodsuch as offset printing, screen printing, and gravure printing may beused. The offset printing may be performed by using the method in whichafter the paste is filled in the intaglio on which the pattern isformed, first transferring is performed by using silicon rubber that iscalled as the blanket, and the second transferring is performed byclosely contacting the blanket and the transparent substance. The screenprinting may be performed by using the method in which after the pasteis disposed on the screen on which the pattern is formed, the paste isdirectly provided on the substance through the screen that has the spacewhile the squeeze is pushed. The gravure printing may be performed byusing the method in which after the paste is filled in the pattern whilethe blanket where the pattern is formed on the roil is wound, it istransferred on the transparent substance. In the present invention, theabove method may be used and the above methods may be used incombination. In addition, the other printing method that is known tothose who are skilled in the art may be used.

In the case of the offset printing method, because of the releaseproperty of the blanket, since most of the paste is nearly transferredon the transparent substance such as glass, a separate blanket washingprocess is not required. The intaglio may be manufactured by preciselyetching the glass on which the desired conductive heating line patternis formed, and metal or DLC (diamond-like carbon) coating may beperformed on the glass surface for the durability. The intaglio may bemanufactured by etching the metal plate.

In the present invention, in order to implement the more preciseconductive heating line pattern, it is preferable to use the offsetprinting method. FIG. 3 illustrates the offset printing method.According to FIG. 3, after the paste is filled in the pattern of theintaglio by using the doctor blade as the first step, the firsttransferring is performed by rotating the blanket, and as the secondstep, the second transferring is performed on the surface of thetransparent substance by rotating the blanket.

In the present invention, it is not limited to the above printingmethod, and the photolithography process may be used. For example, thephotolithography process may be performed by using the method in whichthe conductive heating line pattern material layer is formed on theentire surface of the transparent substance, the photoresist layer isformed thereon, the photoresist layer is patterned by the selectiveexposure and developing process, the conductive heating line patternmaterial layer is patterned by using the patterned photoresist layer asthe mask, and the photoresist layer is removed.

The present invention may use the photolithography method. For example,after the picture photosensitive material that includes silver halide iscoated on the transparent substance, the pattern may be formed byselectively exposing and developing the photosensitive material. Adetailed example will be described below. First, the photosensitivematerial for negative is coated on the substance on which the patternwill be formed. In this case, as the substance, a polymer film such asPET, acetyl celluloide and the like may be used. The polymer filmmaterial on which the photosensitive material is coated is called as thefilm. The photosensitive material for negative was formed of silverhalide in which AgBr that was very sensitive to light and regularlyreacted with it and a small amount of AgI were mixed with each other.Since the image that is developed by picturing the generalphotosensitive material for negative is a negative picture that isopposite to the subject in terms of light and shade, the picturing maybe performed by using the mask that has the pattern form that will beformed and preferably irregular pattern form.

In order to increase the conductivity of the heating line pattern thatis formed by using the photolithography and photography process, aplating treatment may be further performed. The plating may use anelectroless plating method, copper or nickel may be used as the platingmaterial, and after the copper plating is performed, nickel plating maybe performed thereon, but the scope of the present invention is notlimited thereto.

The present invention may use the method using the mask. For example,after the mask that has the heating pattern is disposed close to thesubstance, it may be patterned by using the method for depositing theheating pattern material. In this case, the depositing method may use aheat deposition method by heat or electron beam, a PVD (physical vapordeposition) method such as sputter, and a CVD (chemical vapordeposition) method using an organometal material.

In the present invention, the transparent substance is not particularlylimited, but is preferable to use the substrate where the lightpermeability is 50% or more, and preferably 75% or more. In detail,glass may be used as the transparent substance, and the plasticsubstrate or plastic film may be used. In the case of when the plasticfilm is used, it is preferable that after the conductive heating linepattern is formed, glass is attached on at least one side of thesubstrate. In this case, it is more preferable that the glass or plasticsubstrate is attached to the side on which the conductive heating linepattern is formed. A material that is known in the art may be used asthe plastic substrate or film, for example, it is preferable to use thefilm that has the visible ray permeability of 80% or more such as PET(Polyethylene terephthalate), PVB (polyvinylbutyral), PEN (polyethylenenaphthalate), PES (polyethersulfon), PC (polycarbonate), and acetylcelluloide. The thickness of the plastic film is preferably 12.5 to 500micrometers, and more preferably 50 to 250 micrometers.

In the present invention, it is preferable that as the conductiveheating material, metal that has an excellent thermal conductivity isused. In addition, the specific resistance value of the conductiveheating line material is in the range of 1 microOhm cm to 200 microOhmcm. As a detailed example of the conductive heating line material,copper, silver, carbon nanotube (CNT) may be used, and silver is mostpreferable. The conductive heating line material may be used in aparticle form. In the present invention, as the conductive heating linematerial, copper particles that are coated with silver may be used.

In the present invention, in the case of when the paste that includesthe conductive heating line material is used, the paste may furtherinclude an organic binder in addition to the conductive heating linematerial so as to easily perform the printing process. It is preferablethat the organic binder has a volatile property in the sinteringprocess. As the organic binder, there are polyacryl resin, polyurethaneresin, polyester resin, polyolefine resin, polycarbonate resin andcellulose resin, polyimide resin, polyethylene naphthalate resin anddenatured epoxy resin, but it is not limited thereto.

In order to improve the attachment ability of the paste to thetransparent substance such as glass, the paste may further include aglass frit. The glass frit may be selected from commercial products, butit is preferable to use the environmentally friendly glass frit thatincludes no lead component. In this case, it is preferable that theaverage diameter of the glass frit is 2 micrometers or less and themaximum diameter thereof is 50 micrometers or less.

If necessary, a solvent may be further added to the paste. As thesolvent, there are butyl carbitol acetate, carbitol acetate,cyclohexanon, cellosolve acetate) and terpineol, but it is not limitedthereto.

In the present invention, in the case of when the paste that includesthe conductive heating line material, organic binder, glass frit andsolvent is used, it is preferable that the weight ratio of theconductive heating line material is 50 to 90%, the weight ratio of theorganic binder is 1 to 20%, the weight ratio of the glass frit is 0.1 to10% and the weight ratio of the solvent is 1 to 20%.

It may be formed so that the line width of the conductive heating lineis 100 micrometers or less, preferably 30 micrometers or less, morepreferably 25 micrometers or less.

In the present invention, in the case of when the above paste is used,if the paste is sintered after it is printed in the above pattern, theheating line pattern that has the conductivity is formed. In this case,the sintering temperature is not particularly limited, but it may be 500to 800° C. and preferably 600 to 700° C. In the case of when thetransparent substance that forms the heating line pattern is glass, ifnecessary, in the above sintering step, the glass may be shaped for thepurpose of construction or vehicles. For example, in the step forshaping the glass for vehicles in a curved line, the paste may besintered. In addition, in the case of when the plastic substrate or filmused as the transparent substance that forms the conductive heatingpattern, it is preferable that the sintering is performed at arelatively low temperature. For example, it may be performed at 50 to350° C.

In the method for manufacturing the heating element according to anexemplary embodiment of the present invention, the step for forming thebus bar that is electrically connected to the conductive heating lineand the step for providing the power portion that is connected to thebus bar are performed. These steps may use a method that is known in theart. For example, the bus bar may be simultaneously formed inconjunction with the formation of the conductive heating line, and maybe formed by using the same or other printing method after theconductive heating pattern is formed. For example, after the conductiveheating line is formed by using the offset printing method, the bus barmay be formed through the screen printing. In this case, it isappropriate that the thickness of the bus bar is 1 to 100 micrometersand it is preferably 10 to 50 micrometers. If it is less than 1micrometer, since the contact resistance between the conductive heatingline and the bus bar is increased, local heating may be performed atcontact portion, and if it is more than 100 micrometers, the cost of theelectrode material is increased. The connection between the bus bar andpower may be performed through soldering and physical contact to thestructure that has good conductive heating.

In order to conceal the conductive heating line and the bus bar, theblack pattern may be formed. The black pattern may be printed by usingthe paste that includes cobalt oxides. In this case, it is appropriatethe printing method is the screen printing, and its thickness is 10 to100 micrometers. The conductive heating line and the bus bar may beformed before or after the black pattern is formed.

The heating element according to an exemplary embodiment of the presentinvention includes an additional transparent substance that is providedon a side on which the conductive heating line of the transparentsubstance is provided. When the additional transparent substance isattached, an adhesive film may be provided between the conductiveheating line and additional transparent substance. In the course ofattaching them, the temperature and pressure may be controlled.

In one detailed embodiment, the attachment film is inserted between thetransparent substance on which the conductive heating pattern is formedand additional transparent substance, and they are put into the vacuumbag, and reduced in pressure or increased in temperature or increased intemperature by using the hot roll, thus removing the air, therebyaccomplishing the first attachment. In this case, the pressure,temperature and time may vary according he kind of the attachment film,and in general, the temperature may be gradually increased from normaltemperature to 100° C. at a pressure of 300 to 700 Torr. In this case,it is preferable that the time is generally 1 hour or less. Thepreliminarily attached layered structure that is first attached issubjected to the second attachment process by the autoclave processwhere the temperature is increased while the pressure is added in theautoclave. The second attachment varies according to the kind of theattachment film, but it is preferable that after the attachment isperformed at the pressure of 140 bar or more and the temperature in therange of 130 to 150° C. for 1 to 3 hours, and preferably about 2 hours,it is slowly cooled.

In the other detailed embodiment, the method for attaching them throughone step by using the vacuum laminator device unlike the above two stepattachment process may be used. The attachment may be performed bystepwisely increasing the temperature to 80 to 150° C. and cooling themso that the pressure is lowered (˜5 mbar) until the temperature is 100°C. and thereafter the pressure is added (˜1000 mbar).

Here, any material that has an adhesive strength and is transparentafter attaching may be used as the material of the adhesive film. Forexample, the PVB film, EVA film, PU film and the like may be used, butis not limited thereto. The adhesive film is not particularly limited,but it is preferable that its thickness is in the range of 100micrometers to 800 micrometers.

In the above method, the additional attached transparent substance maybe formed of only the transparent substance and may be formed of thetransparent substance that is provided with the conductive heating linethat is manufactured as described above.

It is preferable that the line width of the conductive heating line ofthe heating element is 100 micrometers or less, preferably 30micrometers or less, more preferably 25 micrometers or less and 5micrometers or more. The interval between the lines of the conductiveheating line is preferably 30 mm or less, preferably 50 micrometers to10 mm, and preferably 200 micrometers to 0.65 mm. The height of theheating line is 1 to 100 micrometers, and more preferably 3 micrometers.The line width and line height of the heating line may be made uniformby the above methods. In the present invention, the uniformity of theheating line may be in the range of ±3 micrometers in the case of theline width and in the range of ±1 micrometer in the case of the lineheight.

The heating element according to an exemplary embodiment of the presentinvention may to the power for heating, and In this case, the heatingamount is 100 to 700 W per m², and preferably 200 to 300 W. Since theheating element according to an exemplary embodiment of the presentinvention has excellent heating performance at the low voltage, forexample, 30 V or less, and preferably 20 V or less, it may be usefullyused in vehicles and the like. The resistance of the heating element is5 ohm/square or less, preferably 1 ohm/square or less, and morepreferably 0.5 ohm/square or less.

The heating element according to an exemplary embodiment of the presentinvention may have a shape of curved surface.

In the heating element according to an exemplary embodiment of thepresent invention, it is preferable that the opening ratio of theconductive heating line pattern, that is, the area ratio of the glassthat is not covered with the pattern is 70% or more. The heating elementaccording to an exemplary embodiment of the present invention has anexcellent heating property where an opening ratio is 70% or more, thetemperature deviation within 5 min after heating operation is maintainedat 10%, and the temperature is increased.

The heating element according to an exemplary embodiment of the presentinvention may be applied to glass that is used for various transportmeans such as vehicles, ships, railroads, high-speed railroads, andairplanes, houses or other buildings. In particular, since the heatingelement according to an exemplary embodiment of the present inventionhas an excellent heating property at a low voltage, can minimize sideeffects by diffraction and interference of light source after sunset,and can be invisible in the above line width, unlike the knowntechnology, it may be applied to the front window for transport meanssuch as vehicles.

Mode for Invention

Hereinafter, the present invention is illustrated through Examples, butthe scope of the present invention is not limited by them.

Example 1

The silver paste was manufactured by dissolving 80 wt % of silverparticles that had the particle diameter of 2 micrometers, 5 wt % ofpolyester resin, 5 wt % of grass frit in 10 wt % of BCA (butyl carbitolacetate) solvent. As the intaglio, the glass that had the width of 20micrometers, the depth of 7.5 micrometers, and the average intervalbetween lines of 600 micrometers and the same pattern as FIG. 1 wasused. In this case, when the straight line that intersected the formedpattern was drawn, the ratio (distance distribution ratio) of standarddeviation in respects to an average value of distances between adjacentintersection points of the straight line and the electric conductivepattern was about 30%.

After the silver pattern was formed on the glass substrate (100 mm×100mm) by using the method that was shown in FIG. 3 and the offset printer,it was sintered at 600° C. for about 3 min to form the heating lineshown in FIG. 1.

The surface resistance of the glass substrate that had the heating linewas 1.2 ohm/square, and the bus bar was formed by contacting the copperstrip on the pattern by the clip in the direction of 100 mm. In thiscase, the resistance between both terminals was 1.5 ohm. In this case,when the voltage of 2.8 V was applied, the heating amount was 5.1 W (510W/m²). As a result of the measurement of the heating phenomenon by usingthe IR vision camera, the temperature was increased from 20° C. to 40°C. within 20 min. In addition, the temperature deviation percentagevalue that was obtained by dividing the difference between the maximumvalue and the minimum value of the temperatures that were measured 20points by the average value was 6% or less for the measurement time. Thevisible ray permeability of the glass that had the heating line was 80%or more

When the equipment shown in KS L 2007 was used, the incandescent lamp of100 W (general bulb having a predetermined brightness was used) wasinstalled at the distance of 7 m from the glass substrate that had theheating line, and light that is emitted from the light source penetratesthe glass substrate that had the heating line, the digital image of1600×1200 pixels was obtained by using. On the basis of the center ofthe light source, the image had the pixels within the distance of 500,the average value of the intensity of light per each 5°, and standarddeviation value of the average values was calculated. The standarddeviation value was 12.1. In addition, predetermined patterns byscattering of light were not observed around the light source.

Example 2

The silver paste was manufactured by dissolving 80 wt % of silverparticles that had the particle diameter of 2 micrometers, 5 wt % ofpolyester resin, 5 wt % of grass frit in 10 wt % of BCA (butyl carbitolacetate) solvent. As the intaglio, the glass that had the width of 20micrometers, the depth of 7.5 micrometers and the same pattern as FIG. 5was used.

After the silver pattern was formed on the glass substrate (100 mm×100mm) by using the method that was shown in FIG. 2 and the offset printer,it was sintered at 600° C. for about 3 min to form the heating lineshown in FIG. 5. In this case, when the straight line that intersectedthe formed pattern was drawn, the ratio (distance distribution ratio) ofstandard deviation in respects to an average value of distances betweenadjacent intersection points of the straight line and the electricconductive pattern was about 50%.

In this case, the surface resistance was 1.0 ohm/square, and resistancebetween both ends of the glass substrate of 100 mm×100 mm was 1.0 ohm.The visible ray permeability of the glass that had the conductiveheating line pattern was 70%.

The light intensity experiment was performed by using the same method asExample 1. In this case, the standard deviation value of the intensityof light for each angle was 5. In addition, predetermined patterns byscattering of light were observed around the light source.

Comparative Example 1

The grid pattern on the basis of the square of 0.09 mm² wasmanufactured, and the figure of the pattern was the same as that of FIG.6. In this case, when the straight line that intersected the formedpattern was drawn, the ratio (distance distribution ratio) of standarddeviation in respects to an average value of distances between adjacentintersection points of the straight line and the electric conductivepattern was about 0%. In this case, the surface resistance was 0.4ohm/square, and resistance between both ends of the glass substrate of100 mm×100 mm was 0.4 ohm. The visible ray permeability of the patternedglass was 74%. The light intensity experiment was performed by using thesame method as Example 1. In this case, the standard deviation value ofthe intensity of light for each angle was 19.5. In addition, the stronginterference patterns that had the cross shape were observed around thelight source.

Comparative Example 2

The same pattern as that of FIG. 7 was manufactured (pitch 0.3 mm). Inthis case, when the straight line that intersected the formed patternwas drawn, the ratio (distance distribution ratio) of standard deviationin respects to an average value of distances between adjacentintersection points of the straight line and the electric conductivepattern was about 0%. In this case, the surface resistance was 0.8ohm/square, and resistance between both ends of the glass substrate of100 mm×100 mm was 0.79 ohm. The visible ray permeability the patternedglass was 70%.

Example 3

The photosensitive material for negative was coated on the PET filmsubstrate on which the pattern will be formed. The photosensitivematerial negative was formed of silver halide in which AgBr that wasvery sensitive to light and regularly reacted with it and a small amountof AgI were mixed with each other. The irregular pattern that was formedon the PET film substrate was the same as the pattern of Example 1. Byusing the negative mask that was configured that light was penetratedthrough the designed pattern area and light was not penetrated through aportion that did not correspond to the pattern, light was irradiated tothe film according to the set exposure time and intensity of light. Bythis process, photosensitive silver on the photosensitive emulsion layerwas photosensitized to form a latent image. The inversion pattern of themask pattern was formed in a visible phase by converting photosensitivesilver into blackened silver through the development process of theformed latent image. The properties of the pattern that was made ofblackened silver formed on the PET film substrate through the photographprocess.

TABLE 1 Line width Line height (micrometer) (micrometer ) Permeability(%) 20 6.5 75.6

The film was laminated on the glass by using the adhesive film. In thiscase, the surface resistance was 0.1 ohm/square, and resistance betweenboth ends of the glass substrate of 100 mm×100 mm was 0.2 ohm. The lightintensity experiment was performed by using the same method asExample 1. In this case, the standard deviation value of the intensityof light for each angle was 12.1. In addition, predetermined patterns byscattering of light were not observed around the light source.

1. A heating element comprising a transparent substance; a conductiveheating line that is provided on at least one side of the transparentsubstance; bus bars that is electrically connected to the conductiveheating line; and a power portion that is connected to the bus bars,wherein 30% or more of the entire area of the transparent substance hasa conductive heating line pattern in which, when a straight line thatintersects the conductive heating line is drawn, a ratio (distancedistribution ratio) of standard deviation in respects to an averagevalue of distances between adjacent intersection points of the straightline and the conductive heating line is 2% or more.
 2. The heatingelement according to claim 1, wherein the straight line that intersectsthe conductive heating line is a line in which the standard deviation ofthe distances between adjacent intersection points of the straight lineand the conductive heating line is the smallest value.
 3. The heatingelement according to claim 1, wherein the straight line that intersectsthe conductive heating line is a straight line that vertically extendsin respects to the tangent line of any one point of the conductiveheating line.
 4. The heating element according to claim 1, wherein thestraight line that intersects the conductive heating line has 80 or moreintersection points of the straight line and the conductive heatingline.
 5. The heating element according to claim 1, wherein the ratio(distance distribution ratio) of standard deviation in respects to theaverage value of distances between adjacent intersection points of thestraight line that intersects the conductive heating line and theconductive heating line is 20% or more.
 6. The heating element accordingto claim 1, wherein the conductive heating line has a boundary typepattern of figures that form a Voronoi diagram.
 7. The heating elementaccording to claim 1, wherein in the conductive heating line, a linewidth is 100 micrometers or less, an interval between lines is 30 mm orless, and a height of the line from the surface of the transparentsubstance is in the range of 1 to 100 micrometers.
 8. The heatingelement according to claim 1, wherein the other transparent substance isfurther provided on a side on which the conductive heating line of thetransparent substance is provided.
 9. The heating element according toclaim 1, wherein the permeability deviation in respects to apredetermined circle that has a diameter of 20 cm is 5% or less.
 10. Theheating element according to claim 1, wherein after heating, a standarddeviation of the surface temperature of the transparent substance iswithin 20%.
 11. The heating element according to claim 10, wherein thetransparent substance is glass, plastic substrate or plastic film. 12.The heating element according to claim 10, wherein in the heatingelement, an opening ratio is 70% or more, a surface resistance is 5ohm/square or less, and a heating amount is 100 to 500 W per m².
 13. Theheating element as set forth in claim 10, wherein the heating elementincludes at least two areas that have different patterns that areconfigured by the conductive heating line.
 14. The heating element asset forth in claim 10, wherein the heating element includes an area inwhich the conductive heating line is not formed.
 15. The heating elementas set forth in claim 10, wherein the conductive heating line isblackened.
 16. The heating element as set forth in claim 10, wherein theheating element is for a front window of vehicles.
 17. The heatingelement as set forth in claim 1, wherein the standard deviation value ofthe intensity of light for each 5° in a circumferential direction of thelight source which is measured when the light emitted from the lightsource that is disposed at the distance of 7 m from the heating elementpasses through the heating element is 15 or less.
 18. A heating elementcomprising: a transparent substance; a conductive heating line that isprovided on at least one side of the transparent substance; bus barsthat is electrically connected to the conductive heating line; and apower portion that is connected to the bus bars, wherein the standarddeviation value of the intensity of light for each 5° in acircumferential direction of the light source which is measured when thelight emitted from the light source that is disposed at the distance of7 m from the heating element passes through the heating element is 15 orless.
 19. The heating element according to claim 18, wherein thepermeability deviation in respects to a predetermined circle that has adiameter of 20 cm is 5% or less.
 20. The heating element according toclaim 18, wherein the standard deviation of the surface temperature ofthe transparent substance after heating is within 20%.
 21. (canceled)22. (canceled)
 23. (canceled)
 24. (canceled)